Detrital zircon grains were collected from seven layers of sandstones along the paleomagnetically well-dated Cenozoic sequence in the Jingou River section on the northern piedmont of the Tianshan Mountains. As compared with the lithostratigraphic distribution in the drainage reaches, it reveals that the central Tianshan Mountains began to uplift as a provenance and subjected to erosion in as late as late Oligocene, then these processes extended to the southern margin of the northern Tianshan around the early Miocene, and finally to the whole northern Tianshan Mountains. Around mid and late Miocene the northern Tianshan Mountains began to prominently uplift and gradually impeded the supply of sediments from central Tianshan Mountains and finally became the major provenance.